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Marchi A.,University of Adelaide | Dandy G.,University of Adelaide | Wilkins A.,SA Water | Rohrlach H.,Tonkin Consulting
Journal of Water Resources Planning and Management | Year: 2014

In recent years, a number of evolutionary algorithms have been proposed for optimizing the design and operation of water distribution systems (WDSs). These evolutionary algorithms include genetic algorithms, ant colony optimization, particle swarm optimization, the shuffled leaping frog algorithm, and differential evolution. Although there have been some comparisons made of the performance of the various algorithms, very few of these comparisons have been carried out in a completely rigorous manner. The main aim of this paper is to introduce a methodology for the rigorous comparison of various algorithms for the optimum design of water distribution systems. The methodology involves comparing the various algorithms in terms of (1) the best solution obtained; (2) the speed of convergence; and (3) the spread and consistency of the solutions obtained over a number of random starting seeds and numbers of evaluations. As a demonstration of the methodology, the techniques of genetic algorithms (GA), particle swarm optimization (PSO), and differential evolution (DE) are applied to two frequently used WDS case studies, namely the New York Tunnels and Hanoi water networks. In addition, the techniques are applied to a real-size water distribution system consisting of 476 pipes. The results obtained show that the algorithm performances depend on the specific problem and the number of function evaluations allowed. Moreover, it is shown that correct calibration is an essential phase for a fair comparison of evolutionary algorithms. In fact, the best parameters are a function of the problem characteristics, of the objective function and of the variants in the algorithm operators. Therefore the adoption of configurations tested on slightly different versions of the algorithms can lead to quite different results. © 2014 American Society of Civil Engineers.

Wong A.,University of Adelaide | Vince P.,SA Water | Gamboa E.,University of Adelaide
Annual Conference of the Australasian Corrosion Association 2012 | Year: 2012

Pumping is one of the major costs in many industries that require liquid transportation. By improving pump efficiency, significant energy and cost savings can be achieved. One of the methods that are used to improve pumping efficiency is to apply an anticorrosion coating to the pump internal surfaces. The coatings trialled in this project are two ceramic filled epoxies from two different suppliers, and an epoxy from a third supplier. These were trialled on two pumps and pump efficiencies were measured over a ten year period. Results are presented and compared. It was found that ceramic filled epoxies achieved the best performance in these examples. It was also found that regular pump testing is an ideal method to evaluate pump performance and can be used to schedule major overhauls. Copyright © (2012) by the Australasian Corrosion Association.

Hrudey S.E.,University of Alberta | Backer L.C.,Centers for Disease Control and Prevention | Humpage A.R.,SA Water | Krasner S.W.,Metropolitan Water District of Southern California | And 4 more authors.
Journal of Toxicology and Environmental Health - Part B: Critical Reviews | Year: 2015

Exposure to chlorination disinfection by-products (CxDBPs) is prevalent in populations using chlorination-based methods to disinfect public water supplies. Multifaceted research has been directed for decades to identify, characterize, and understand the toxicology of these compounds, control and minimize their formation, and conduct epidemiologic studies related to exposure. Urinary bladder cancer has been the health risk most consistently associated with CxDBPs in epidemiologic studies. An international workshop was held to (1) discuss the qualitative strengths and limitations that inform the association between bladder cancer and CxDBPs in the context of possible causation, (2) identify knowledge gaps for this topic in relation to chlorine/chloramine-based disinfection practice(s) in the United States, and (3) assess the evidence for informing risk management. Epidemiological evidence linking exposures to CxDBPs in drinking water to human bladder cancer risk provides insight into causality. However, because of imprecise, inaccurate, or incomplete estimation of CxDBPs levels in epidemiologic studies, translation from hazard identification directly to risk management and regulatory policy for CxDBPs can be challenging. Quantitative risk estimates derived from toxicological risk assessment for CxDBPs currently cannot be reconciled with those from epidemiologic studies, notwithstanding the complexities involved, making regulatory interpretation difficult. Evidence presented here has both strengths and limitations that require additional studies to resolve and improve the understanding of exposure response relationships. Replication of epidemiologic findings in independent populations with further elaboration of exposure assessment is needed to strengthen the knowledge base needed to better inform effective regulatory approaches. © Copyright © Steve E. Hrudey, Lorraine C. Backer, Andrew R. Humpage, Stuart W. Krasner, Dominique S. Michaud, Lee E. Moore, Philip C. Singer, Benjamin D. Stanford.

Burnell R.,Australian Water Environments | Bekesi G.,Australian Water Environments | Telfer A.,Australian Water Environments | Forward P.,SA Water | Porter B.,Water and Natural Resources
Australian Journal of Water Resources | Year: 2013

In addition to the threat posed by high salinity to drinking water, increased salinity in the River Murray also represents a threat to the health of floodplains, wetlands and may increase the costs of infrastructure maintenance. In the Lower Murray Basin most of the salts in the river originate from groundwater. Run of river salinity surveys are used to measure salt inflow. They measure electrical conductivity every kilometre over five consecutive days, at low and steady river flows. For a robust interpretation of salt inflow, the background electrical conductivity has to be removed from the measurements. The existing methodology is robust for analysing cumulative salt inflows over river reaches but assigns salt inflows up to several kilometres downstream from where they actually occur. A new method has therefore been developed to assign the salt inflow more closely to the location where it actually occurs and at the correct rate. The new methodology is based on the assumptions that salt inflow is the function of space only (during the survey) and the background conductivity can be described by the temporal variations observed at a fixed location. These in turn allow better targeting of the high salt inflow zones for salt interception. © Institution of Engineers Australia, 2013.

Majewski P.,University of South Australia | Luong J.,SA Water | Stretton K.,Scaled Management Systems Pty Ltd.
Water Science and Technology | Year: 2012

The removal of sucrose and fructose from water at various high concentrations by surface engineered silica (SES) was studied using dissolved sugar in pure water. The results indicate that sugar at concentrations of up to 800 g/L can be removed by SES at a relatively high dose of 250 to 300 g/L. Based on these results, process water from a soft drink filling station which was contaminated by sugar, flavour components, Escherichia coli, Pseudomonas aeruginosa bacteria and Candida pelliculosa yeast were treated to study the performance of SES using actual process water samples by analysing turbidity, biological oxygen demand (BOD), UV absorption, and various other standard parameters, and microbial tests. The study shows that at a dose of 100 g/L of SES bacterial contamination as well as turbidity, BOD and UV absorption can be significantly reduced. However, the study found the yeast species Candida pelliculosa could not be removed from the water samples. © IWA Publishing 2012.

Reid K.,SA Water | Dixon M.,SA Water | Dixon M.,University of South Australia | Pelekani C.,SA Water | And 3 more authors.
Desalination | Year: 2014

Biofouling compromises the efficiency of membrane desalination systems, especially energy and product water quality. Feed spacers employed in conventional spiral wound membranes create turbulence to minimise concentration polarisation. Research demonstrates that feed spacers can enhance biological growth within membrane elements. In combination with the strong link between fouling and surface hydrophobicity chemical modification of feed spacers could help counteract biofouling potential. In this study, an evaluation of feed spacers coated with diglyme using plasma polymerisation was assessed. Low energy density treatment was associated with an increase in biofouling, compared with the control, consistent with insufficient cross-linking of the diglyme monomer to the spacer surface. Increasing energy density treatment resulted in fouling performance approaching that of, or slightly better than the control. It is possible that batch recirculation type experiments may not best facilitate assessment of biofouling potential in single-pass cross-flow membrane systems. The study demonstrated that plasma treatment of conventional feed spacers has potential to reduce affinity for bacterial attachment, and may provide a viable and complementary approach to direct membrane surface modification for biofouling control. Further studies to quantify changes associated with diglyme plasma polymerisation and establish optimum conditions for biofouling minimisation are recommended. © 2013 Elsevier B.V.

Three drinking water storage reservoirs in subtropical southeast Queensland, Australia have regular blooms of the toxic cyanobacterium Cylindrospermopsis raciborskii that can produce cylindrospermopsins. We tested water samples from 16 sites in 3 reservoirs on 2 sampling occasions during a bloom of C. raciborskii in the austral summer and autumn of 2007. Using a range of parameters including quantitative real-time PCR, microscope cell counts and HPLC-MS/MS we correlated the 16S ribosomal RNA gene with total cyanobacteria, the rpoC1 gene with C. raciborskii cell concentrations, and the cyrC gene with cylindrospermopsin concentrations to assess spatial and temporal variability within and between reservoirs. While the correlation between cyrC and cylindrospermopsin cell quotas was good (mean r2 = 0.61 for February samples and 0.75 for March samples), the correlation between total cyanobacteria and the 16S ribosomal RNA gene, and between C. raciborskii and the rpoC1 gene were poor indicating that further work is needed to develop these novel molecular methods. Spatial and temporal analysis of the distribution of rpoC1, cylindrospermopsin cell quotas, and a range of physical and chemical water quality parameters showed the greatest variation occurred between reservoirs, and within the largest and most spatially diverse reservoir. This suggests that populations of C. raciborskii strains with inherently different cylindrospermopsin cell quotas may be an important driver of toxicity in these reservoirs. An outcome of this study was the observation that deoxycylindrospermopsin always exceeded the cylindrospermopsin cell quota by up to 5-fold, and that a peak cell quota of 60 fg (cylindrospermopsin + deoxycylindrospermopsin) cell-1 was measured. Crown Copyright © 2009.

Erdmann B.,SA Water | Vince P.,SA Water
50th Annual Conference of the Australasian Corrosion Association 2010: Corrosion and Prevention 2010 | Year: 2010

Barrages were constructed at five locations near the River Murray mouth in the mid 1940's to stop saltwater incursions into the river. In 2006 a project to replace the existing concrete deck at two of the Barrages commenced. The design consisted of steel reinforced concrete deck and supporting beams. Stainless steel reinforcement was utilised in locations of low concrete cover. In 2008 corrosion staining was reported on the decks and support beams. Closer examination found that the ends of stainless steel spacer bars and ferrules supporting the handrails on the deck units were corroding. The Barrages are located in a very aggressive environment with wind driven sea spray providing an environment that is conducive to high corrosion rates. It was noted, however, that existing fittings of the same grade of stainless steel had been in place for more than 40 years and had not suffered the same level of corrosion. This paper details the investigation of these defects which found that the stainless steel fabrication procedures and the quality of the stainless steel contributed to the failure. An extensive investigation was undertaken to determine the cause of the corrosion, the design of the units modified to incorporate these learnings into future units, and a trial program instigated to find the best method for repairing the corroded components in order to meet the design life requirements of the Barrages. Observations and conclusions are reported.

Ayala V.,Chrysler Group LLC | Kildea T.,SA Water | Artal J.,Chrysler Group LLC
Desalination and Water Treatment | Year: 2015

Abstract: Desalination has come to the fore in Australia as a means of “water proofing” Australian coastal cities against drought. The construction of large desalination plants along Australia’s coastline has generated considerable public debate, which has required plant operators to provide assurance that the protection of the local environment is a strong core value in the developments. The dispersion of the saline concentrate reject from these plants has been the focus of numerous modelling and monitoring studies, as rapid dilution is required to minimise potential impacts to the local marine environment from high salinity concentrations. The plant is designed to produce potable water at different rates dependent upon the city’s demand at different times of the year. This variable flow creates a challenge as the velocity of the saline discharge being dispersed through the outfall can dramatically change, influencing dilution. The Adelaide Desalination Plant utilises duckbill valves to rapidly disperse the saline concentrate waste stream into the local marine environment. The results to date have shown that this novel engineering solution has increased the dispersion of the saline waste at low flows, protecting the local marine environment from the adverse effects of concentrated salt water. © 2014 Balaban Desalination Publications. All rights reserved.

Crozier R.,Waterlink | Foster J.,Waterlink | Fumex A.,SA Water
14th Water Distribution Systems Analysis Conference 2012, WDSA 2012 | Year: 2012

SA Water in 2009 commenced the North South Interconnection System Project (NSISP) as part of the Network Water Security Program (NWSP). The NSISP will effectively re-design how the Adelaide water supply system operates by inter-connecting the network via a number of large pipe, pump station and ancillaries works. The transfer infrastructure will provide the capability to utilise water from the new Adelaide Desalination Plant (ADP) and also for flexibility and network security gains. Waterlink, a joint venture of three Engineering Consultants, was engaged by SA Water to undertake the concept and detailed design work for the NSISP. This paper presents an overview of the NSISP and the role the Waterlink network modelling team has played in the effective planning and sizing of infrastructure from a hydraulic and water quality perspective. The modelling approach and effort undertaken enabled the development of the concept design with the confidence required to secure full financial approval for the project in late 2010; development of fit-for-purpose and innovative detailed designs for the required new infrastructure to meet the project objectives and the implementation of the construction work to occur with minimal impact on SA Water's customers. Copyright © (2012) by Engineers Australia.

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